The Validation &Pathology Core consists of personnel with expertise in clinical gastroenterology, advanced procedures (endoscopic mucosal resection, endoscopic ultrasound), specimen processing, molecular biology, and pathology. Core personnel have many years experience in validation methods. The specific role of this BETRNet Specialized Research Rescource (Core) is to support the Research Center in the design and analysis of validation studies for the binding activity of fluorescent-labeled peptides to high-grade dysplasia and early adenocarcinoma for imaging in Barrett's esophagus. This Core will also support the three Primary Research Projects, developmental (Pilot) projects, cross-BETRNet projects, and other cross-BETRNet activities by providing methods and services for pathological evaluation of tissue specimens, including EMR and biopsy.